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.net core中实现服务自动发现
source link: https://www.cnblogs.com/TianFang/p/17865748.html
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.net core中自带了依赖注入框架，asp.net core或worker框架下可以直接使用， 控制台程序可以通过加入Microsoft.Extensions.DependencyInjection程序包来支持。自带的di框架功能还行， 但是一个不方便的地方是没有提供服务自动发现、注册的接口，稍微大的程序都是需要通过反射自己写一个发现程序的。
今天网上找到了一个第三方实现的服务发现的库Scrutor，还比较好用， 示例如下：
var collection = new ServiceCollection(); collection.Scan(scan => scan // We start out with all types in the assembly of ITransientService .FromAssemblyOf<ITransientService>() // AddClasses starts out with all public, non-abstract types in this assembly. // These types are then filtered by the delegate passed to the method. // In this case, we filter out only the classes that are assignable to ITransientService. .AddClasses(classes => classes.AssignableTo<ITransientService>()) // We then specify what type we want to register these classes as. // In this case, we want to register the types as all of its implemented interfaces. // So if a type implements 3 interfaces; A, B, C, we'd end up with three separate registrations. .AsImplementedInterfaces() // And lastly, we specify the lifetime of these registrations. .WithTransientLifetime() // Here we start again, with a new full set of classes from the assembly above. // This time, filtering out only the classes assignable to IScopedService. .AddClasses(classes => classes.AssignableTo<IScopedService>()) // Now, we just want to register these types as a single interface, IScopedService. .As<IScopedService>() // And again, just specify the lifetime. .WithScopedLifetime() // Generic interfaces are also supported too, e.g. public interface IOpenGeneric<T> .AddClasses(classes => classes.AssignableTo(typeof(IOpenGeneric<>))) .AsImplementedInterfaces() // And you scan generics with multiple type parameters too // e.g. public interface IQueryHandler<TQuery, TResult> .AddClasses(classes => classes.AssignableTo(typeof(IQueryHandler<,>))) .AsImplementedInterfaces());
这个类本身是比较好用的，但是它仍需要手工制定程序集作为扫描范围。 这个程序集的范围并不是所有程序集，往往只有用户代码程序集， asp.net core程序内部是有这个功能的，例如它内部就能扫描所有用户程序集，生成ApiController，网上搜了一下，发现还是一个内部接口，不过可以通过反射来调用：
public static Assembly[] GetAssemblies() { var manager = new ApplicationPartManager(); var method = manager.GetType() .GetMethod("PopulateDefaultParts", BindingFlags.NonPublic | BindingFlags.Instance); //加载入口程序集的依赖项树中的所有非官方包的依赖程序集 var assembly = Assembly.GetEntryAssembly().FullName; method.Invoke(manager, new object[] { assembly }); return manager.ApplicationParts.OfType<AssemblyPart>().Select(i => i.Assembly).ToArray(); }
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